EP1310273A1 - Foam fire extinguishing plant - Google Patents

Abstract

The fire protection installation divides the protected space into sectors. Each sector has multiple thermal detectors (10) distributed over the sector and closing a compressed air conduit (12). If a high temperature is detected, the conduit is opened to atmosphere, and the drop in air pressure detected by a controller (16) which generates foam sprayed from all outlets (26) in the sector.

Description

The present invention relates to installations for protection against fires. It relates, more particularly, to a detection and fire extinguisher well suited to fighting fires in large enclosed spaces, such as tunnels, parking lots or warehouses.

• à réponse rapide, c'est-à-dire réagissant instantanément à une élévation anormale de la température, et
• fiables, c'est-à-dire aussi peu sensibles que possible aux changements de température (gel, ...) mais également aux poussières ou autres salissures risquant de les "aveugler" partiellement ou totalement.

Such an installation must, first of all, be equipped with detectors:

• rapid response, i.e. reacting instantly to an abnormal rise in temperature, and
• reliable, that is to say as insensitive as possible to temperature changes (frost, ...) but also to dust or other dirt which risks partially or completely "blind" them.

A fire-fighting installation in a large space must also be capable of responding, in a targeted manner, to several separate fires each other, which is common in an arson or when, in a tunnel, a first fire causes chain collisions and new fires. It is therefore vital that the installation takes place at this location and is not prematurely out of extinction because it has too quickly exhausted its resources on the first fire.

Due to the progress made in the field of foaming agents (usually liquid soaps), foam extinguishing systems have recently experienced strong development. Fire attack by means foam is not only more effective than a simple water installation, called "sprinkler", because it smothers the fire instead of bringing it oxygen, but it also uses a lot less water, which is considerable advantage in tunnels. Note, for example, that a medium expansion installation, well suited to this kind of space, requires only 1 liter of water to produce some 100 liters of foam.

The object of the present invention is to provide an installation for detecting and that meets the requirements set out above and, among other things solutions, attack the fire with foam.

• une pluralité de détecteurs thermiques répartis dans le secteur, obturant chacun l'extrémité d'un conduit alimenté en air comprimé et réagissant à une élévation anormale de la température ambiante en faisant déboucher ledit conduit à l'air libre,
• une pluralité de buses d'extinction à mousse réparties à la partie supérieure du secteur, et
• des moyens de commande qui répondent à une chute de pression résultant de la mise à l'air libre d'au moins l'un desdits conduits par l'alimentation de toutes les buses du secteur en un mélange d'eau sous pression et d'émulseur leur permettant de déverser de la mousse d'extinction sur ce secteur.

More specifically, the invention relates to a fire detection and extinguishing installation in an enclosed space, which comprises a plurality of separate assemblies each assigned to protecting a sector of said space and comprising, for each sector :

• a plurality of thermal detectors distributed in the sector, each blocking the end of a pipe supplied with compressed air and reacting to an abnormal rise in ambient temperature by opening said pipe in the open air,
• a plurality of foam extinguisher nozzles distributed in the upper part of the sector, and
• control means which respond to a pressure drop resulting from the venting of at least one of said conduits by supplying all the nozzles in the sector with a mixture of pressurized water and foam concentrate allowing them to pour extinguishing foam on this sector.

Preferably, each set further comprises means which also respond to said pressure drop by stopping the supply of compressed air from sector detectors to maintain pressure from detectors in other sectors.

It is advantageous, in a tunnel, that each sector has a length about 15 to 20 meters.

• des moyens pour produire un jet pulvérisé d'un mélange d'eau et d'émulseur, et
• des moyens pour recevoir ce jet, enrichi par l'air aspiré sur son trajet, briser les gouttes du liquide reçu en plus fines particules et ainsi produire un jet de mousse.

According to a particularly advantageous embodiment of the invention, the nozzles according to the invention comprise:

• means for producing a spray of a mixture of water and foam concentrate, and
• means for receiving this jet, enriched by the air sucked in on its path, breaking up the drops of the liquid received into finer particles and thus producing a jet of foam.

• les moyens pour produire un jet pulvérisé comportent une chambre de brassage sensiblement cylindrique comprenant, du haut vers le bas, un canal d'amenée de liquide axial, un canal d'amenée de liquide horizontal et circulaire, et un canal d'éjection axial communiquant avec les deux canaux d'amenée;
• le canal d'éjection se termine par un cône de diffusion, tandis que le canal d'amenée de liquide horizontal s'étend sur un angle inférieur à 360°, de l'ordre de 240°;
• la chambre de brassage comprend, en outre, une paroi percée d'orifices formant des chicanes, sur laquelle débouche le canal d'amenée de liquide axial;
• le canal d'amenée de liquide horizontal peut déboucher en aval ou en amont de la paroi formant des chicanes;
• lorsque la canal d'amenée horizontal débouche en aval, la chambre de brassage est réalisée en deux parties, l'une, extérieure, comportant, dans sa paroi supérieure, le canal d'amenée de liquide axial et, dans sa paroi verticale, une gorge horizontale à section semi-circulaire, l'autre, intérieure, comportant, à sa partie supérieure, la paroi formant des chicanes et, dans sa paroi verticale, une gorge horizontale à section semi-circulaire qui forme, avec la gorge de la partie extérieure, le canal d'amenée de liquide horizontal.
• l'extrémité du canal d'amenée de liquide horizontal communique avec le canal d'éjection par un canal radial ménagé dans la partie intérieure de la chambre;
• la chambre de brassage est réalisée en cuivre;
• les moyens pour recevoir le jet pulvérisé comportent un grillage en forme de tronc de cône dont la portion centrale est bombée vers le haut.

The foam nozzles also have the following characteristics:

• the means for producing a spray jet comprise a substantially cylindrical mixing chamber comprising, from top to bottom, an axial liquid supply channel, a horizontal and circular liquid supply channel, and an communicating axial ejection channel with the two supply channels;
• the ejection channel ends in a diffusion cone, while the horizontal liquid supply channel extends over an angle less than 360 °, of the order of 240 °;
• the brewing chamber further comprises a wall pierced with orifices forming baffles, onto which the axial liquid supply channel opens;
• the horizontal liquid supply channel can open downstream or upstream from the wall forming baffles;
• when the horizontal supply channel opens downstream, the stirring chamber is made in two parts, one is external, comprising, in its upper wall, the axial liquid supply channel and, in its vertical wall, a horizontal groove with semi-circular section, the other, internal, comprising, at its upper part, the wall forming baffles and, in its vertical wall, a horizontal groove with semi-circular section which forms, with the groove of the part outside, the horizontal liquid supply channel.
• the end of the horizontal liquid supply channel communicates with the ejection channel by a radial channel formed in the interior part of the chamber;
• the brewing chamber is made of copper;
• the means for receiving the spray jet comprise a grid in the form of a truncated cone, the central portion of which is curved upwards.

• la figure 1 est une représentation schématique d'une installation selon l'invention;
• la figure 2 est une vue de dessus d'une buse à mousse équipant cette installation;
• la figure 3 est une vue de face de cette buse en coupe selon II - II; et
• les figures 4 et 5 montrent le gicleur de la buse, respectivement vu en coupe axiale et de dessus.

Other characteristics and advantages of the present invention will emerge from the description which follows, given with reference to the appended drawing, in which:

• Figure 1 is a schematic representation of an installation according to the invention;
• Figure 2 is a top view of a foam nozzle fitted to this installation;
• Figure 3 is a front view of this nozzle in section along II - II; and
• Figures 4 and 5 show the nozzle of the nozzle, respectively seen in axial section and from above.

Figure 1 shows very schematically, seen from the ground, a portion the roof of a road tunnel equipped, approximately every three meters, with a thermal fire detector 10 formed by a glass bulb filled with a liquid with a high coefficient of expansion, such as alcohol, which breaks when the ambient temperature reaches a temperature exceeding approximately 20 ° C average tunnel temperature. This sensitive element, well known to the person skilled in the art, may be of the type sold under the designation "quick response sprinkler".

Each detector 10 is arranged at the end of a duct 12 supplied with air compressed. As long as the temperature is normal, it seals this end but, when an abnormal rise in temperature occurs, it explodes and thus leads to the open air the conduit 12.

According to the invention, the conduits 12 of five contiguous thermal detectors 10 are connected, on the one hand, to the output S of a power supply controller 14 and, on the other hand, at the command input Ec of an extinction controller 16.

In the embodiment described, each group of five detectors 10 thus independently covers a tunnel sector of around fifteen meters long.

The input E of the controller 14 is connected to a single pipe 18 traversing the tunnel and supplied with compressed air by a compressor (not shown). This controller has the function, as long as the detectors 10 of the sector are free, to maintain the pressure in the tubes 12 but, as soon as one of them explodes, due to an abnormal rise in temperature, and thus causes a brutal depression, to cut the food of the group of five detectors concerned in order to maintain pressure groups of detectors from other sectors.

• une entrée E1 reliée à une conduite unique 20 parcourant le tunnel et alimentée en eau sous pression;
• une entrée E2 reliée à un réservoir d'émulseur 22; et
• une sortie S.

The extinction controller 16 has, in addition to the command input Ec:

• an input E1 connected to a single pipe 20 traversing the tunnel and supplied with water under pressure;
• an input E2 connected to a foam concentrate tank 22; and
• an exit S.

The output S of the controller 16 is connected, by a conduit 24, to sets of foam extinguisher nozzles 26 arranged, approximately every three meters, between two detectors 10, under the roof of the tunnel. In the example of realization described, each assembly comprises three nozzles 26 distributed over the width of the tunnel, which will be described later in detail.

The extinction controller 16 has the function of responding to a sudden fall pressure on its Ec input, caused by the explosion of a detector of the sector overheated by a fire, by sending, on its output S, to nozzles 26 of the group concerned with a mixture of water, supplied at its inlet E1, and foam concentrate, supplied at its input E2, allowing them to produce a foam of extinction projected on the fire.

• une vanne manuelle 28 normalement ouverte mais permettant de couper, pour diverses interventions, l'alimentation en air comprimé des cinq détecteurs 10 du groupe;
• un diaphragme 30 servant à limiter le débit d'air;
• une vanne 32 normalement ouverte mais permettant, comme la vanne 28, de couper l'alimentation des cinq détecteurs en air comprimé; et
• un pressostat 34 répondant à une brutale chute de pression par la fermeture de la vanne 32.

More precisely, the power supply controller 14 comprises, from its input E to its output S:

• a manual valve 28 normally open but making it possible to cut, for various interventions, the supply of compressed air to the five detectors 10 of the group;
• a diaphragm 30 serving to limit the air flow;
• a valve 32 normally open but making it possible, like valve 28, to cut the supply of compressed air to the five detectors; and
• a pressure switch 34 responding to a sudden drop in pressure by closing the valve 32.

• une vanne manuelle 36 normalement ouverte mais permettant de couper, pour diverses interventions, l'alimentation en eau des buses 26 du secteur;
• une vanne 38 normalement fermée;
• un pressostat 40 répondant à une brutale chute de la pression à l'entrée Ec par l'ouverture de la vanne 38; et
• un mélangeur venturi 42 dont les deux entrées sont respectivement reliées à la sortie de la vanne 38 et à l'entrée E2 d'amenée de l'émulseur et dont la sortie S alimente, par le conduit 24, les buses 26 du secteur.

The extinction controller 16 comprises, from its input E1 to its output S:

• a manual valve 36 normally open but making it possible to cut, for various interventions, the water supply to the nozzles 26 of the sector;
• a valve 38 normally closed;
• a pressure switch 40 responding to a sudden drop in pressure at the inlet Ec by the opening of the valve 38; and
• a venturi mixer 42, the two inputs of which are respectively connected to the outlet of the valve 38 and to the inlet E2 for supplying the foam concentrate and the outlet S of which supplies, via the conduit 24, the nozzles 26 of the sector.

It will be noted that the valve 38 can also be actuated manually using of an M. order

• d'une part, par le pressostat 34 du contrôleur d'alimentation 14 du secteur concerné, qui ferme sa vanne 32 d'arrivée d'air comprimé afin de ne pas perturber les autres secteurs; et
• d'autre part, par le pressostat 40 du contrôleur d'extinction 16 associé, qui ouvre sa vanne 38 d'arrivée d'eau sous pression pour alimenter les buses d'extinction 26 du secteur.

In summary, the explosion of a thermal detector, following an abnormal rise in temperature in the sector, causes a pressure drop detected:

• on the one hand, by the pressure switch 34 of the supply controller 14 of the sector concerned, which closes its valve 32 of compressed air inlet so as not to disturb the other sectors; and
• on the other hand, by the pressure switch 40 of the associated extinguishing controller 16, which opens its valve 38 for receiving pressurized water to supply the extinguishing nozzles 26 in the sector.

We will now refer to Figures 2 and 3 which represent one of the nozzles 26 of the installation according to the invention. This nozzle has, as elements essentials, a brewing or mixing chamber 50 and a mesh 52.

Chamber 50, advantageously made of copper, has a frame external 54 and a nozzle 56, screwed inside the frame.

The frame 54, which has a roughly cylindrical external shape, delimits a space 58 open downwards, the horizontal upper wall of which carries the reference 60 and the vertical wall reference 62. The frame 54 is associated with a tubular part 64 provided with a thread 66 allowing its connection to a hose for supplying a mixture of water and foam concentrate. Exhibit 64 has an upper channel 68 opening axially at the center of the wall 60 and a lower channel 70 opening tangentially into the wall 62 provided, at this place, of a horizontal groove with a semi-circular section 72 extending substantially at an angle less than 360 °, typically about 240 °.

The nozzle 56, shown in Figures 4 and 5, takes place in the space 58 to the interior of which it is screwed thanks to the thread 74 with which it is provided at its base. When fully screwed, it abuts against the wall 60 of the frame by its end which is pierced, in its central portion, with a network of radial slots 76 also extending substantially over an angle of 240 ° and facing the groove 72 of the frame 54.

Slightly below the slots 76, the nozzle 56 has a groove horizontal with semi-circular section 78 which faces the groove 72 to form a channel 80 communicating at its end with another channel 82 formed radially in the nozzle and opening into a central opening 84 extended downwards by a diffusion cone 86 open to the outside.

Returning to FIGS. 2 and 3, it can be seen that the mesh 52 is arranged facing the cone 86, perpendicularly and coaxially to the brewing chamber 50. This mesh is advantageously made of steel wires from 0.3 to 0.5 mm in diameter. diameter forming meshes from 1 to 1.5 mm side. It has an outer profile in truncated cone and has a central portion 88 slightly curved towards the top, a peripheral portion 90 tilting upwards and a portion of link 92.

The base of the portion 90 is fixed in a metal ring 94 that two arms 96 connect to a ring 98 surrounding the frame 54 of the brewing 50.

In operation, when a pressurized mixture of water and foam concentrate is applied to the nozzle, the upper channel 68 brings part of it to the center of the bottom 60 of the frame. It is thrown axially against the upper face of the nozzle 56 whose network of radial slots 76, constituting baffles, causes the mixing, then it descends into the channel 80 formed by the facing grooves 72 and 78. At the same time, the other part of the mixture under pressure is brought tangentially, through the lower channel 70, at the entrance to the horizontal channel 80 where The two parts of the mixture, which are strongly brewed, therefore meet.

At the end of channel 80, which is 240 ° from its entrance, the water mixture and foam concentrate joins the center of the nozzle through the radial channel 82 from which it is sprayed outwards, with a rotational movement, through the opening 84 and the diffusion cone 86.

Due to the strong mixing of the mixture, it is a jet of large drops, having typically a diameter of 0.6 to 0.8 mm, which when sucking up a quantity significant amount of air is projected onto the screen 52, which breaks the drops in very fine particles, typically 0.1 to 0.2 mm in diameter, to deliver thus an extinguishing foam all the more effective as it is further enriched by the air sucked through the portion 90 of the mesh.

Note that the use of a brewing chamber made of copper contributes to ensuring the stability of the foam produced.

This description has been made with reference to an embodiment in which the horizontal liquid supply channel opens downstream of the chicanes. It will be noted that, according to an alternative embodiment, this channel can also lead upstream of the baffles.

• est équipée de détecteurs thermiques, donc à réponse rapide et insensibles, notamment aux salissures risquant de les "aveugler" partiellement ou totalement;
• est capable de répondre, de manière ciblée, à plusieurs incendies séparés les uns des autres;
• attaque l'incendie à l'aide de mousse, c'est à dire en consommant très peu d'eau et de manière plus efficace qu'en utilisant uniquement de l'eau; et
• est équipée de buses d'extinction à grand "pouvoir moussant" et réalisables en petites dimensions.

Thus, a fire detection and extinguishing installation is carried out which:

• is equipped with thermal detectors, therefore with rapid response and insensitive, in particular to soiling which risks partially or totally "blinding"them;
• is able to respond, in a targeted manner, to several fires separated from each other;
• attacks the fire using foam, that is, consuming very little water and more efficiently than using only water; and
• is equipped with extinguisher nozzles with high "foaming power" and achievable in small dimensions.

Such an installation is therefore very well suited to fighting fires in large enclosed spaces, such as tunnels, parking lots or warehouses.

It should be noted above all that it is particularly well suited for integrating in the gauge of a uni- or bi-directional road tunnel, single lane or two lanes, without restricting the passage of large vehicles.

Claims (15)

Installation for detecting and extinguishing fires in an enclosed space, characterized in that it comprises a plurality of separate assemblies each assigned to the protection of a sector of said space and comprising, for each sector: a plurality of thermal detectors (10) distributed in the sector, each blocking the end of a duct (12) supplied with compressed air and reacting to an abnormal rise in ambient temperature by opening the said duct in the open air, a plurality of foam extinguisher nozzles (26) distributed in the upper part of the sector, and control means (16) which respond to a pressure drop resulting from the venting of at least one of said conduits (12) by supplying all the nozzles (26) of the sector with a mixture of pressurized water and foam concentrate allowing them to pour extinguishing foam on this sector. Installation according to claim 1, characterized in that each assembly further comprises means (14) which also respond to said pressure drop by stopping the supply of compressed air to the detectors (10) of the sector in order to '' ensure that detectors in other sectors are kept under pressure. Installation according to one of claims 1 and 2, characterized in that , for a tunnel, each sector has a length of about 15 to 20 meters. Installation according to claim 1, characterized in that each foam extinguisher nozzle (26) comprises: means for producing a spray of a mixture of water and foam concentrate, and means for receiving this jet, enriched by the air sucked on its path, breaking the drops of the liquid into finer particles and thus producing a jet of foam. Nozzle according to claim 4, characterized in that the means for producing a spray jet comprise a substantially cylindrical mixing chamber (50) comprising, from top to bottom: an axial liquid supply channel (68), a horizontal and circular liquid supply channel (70), and an axial ejection channel (84) communicating with the two supply channels. Nozzle according to claim 5, characterized in that the ejection channel (84) ends in a diffusion cone (86). Nozzle according to claim 5, characterized in that the horizontal liquid supply channel (70) extends over an angle less than 360 °. Nozzle according to one of claims 5 to 7, characterized in that the mixing chamber (50) further comprises a wall pierced with orifices forming baffles (76), onto which the liquid supply channel opens out. axial (68). Nozzle according to claim 8, characterized in that the horizontal liquid supply channel (70) opens downstream of the wall forming baffles (76). Nozzle according to claim 9, characterized in that the mixing chamber (50) is made in two parts, one, external (54), comprising, in its upper wall, the axial liquid supply channel (68) and, in its vertical wall, a horizontal groove with semi-circular section (72), the other, interior (56), comprising, at its upper part, the wall forming baffles (76) and, in its vertical wall, a horizontal groove of semi-circular section (78) which forms, with the groove of the outer part, the horizontal liquid supply channel (70). Nozzle according to claim 10, characterized in that the end of the horizontal liquid supply channel (70) communicates with the ejection channel (84) by a radial channel (82) formed in the interior of the chamber. Nozzle according to claim 8, characterized in that the horizontal liquid supply channel (70) opens upstream of the wall forming baffles (76). Nozzle according to claim 5, characterized in that the brewing chamber (50) is made of copper. Nozzle according to claim 4, characterized in that the means for receiving the spray jet comprise a grid (52) in the form of a truncated cone. Nozzle according to claim 14, characterized in that the central portion (88) of the mesh (52) is curved upwards.

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